Add multi-page app example demonstrating navigation

Add a comprehensive example showing client-side routing:
- Router setup with multiple routes (/, /about, /users, /admin)
- Route parameters (/users/:id) with the NumericIdGuard
- Navigation using Link component and programmatic Navigate/Back
- Route guards with AuthGuard for protected admin page
- Browser history integration with back/forward support

Closes #6

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

examples/multipage/main.go

@@ -0,0 +1,265 @@
+//go:build js && wasm
+
+// Package main demonstrates Iris client-side routing capabilities.
+//
+// This example shows:
+//   - Router setup with multiple routes
+//   - Route parameters (/users/:id)
+//   - Navigation between pages using Link and Navigate
+//   - Route guards for protected routes
+//   - History management (back/forward)
+package main
+
+import (
+	"fmt"
+
+	"git.flowmade.one/flowmade-one/iris/navigation"
+	"git.flowmade.one/flowmade-one/iris/reactive"
+	"git.flowmade.one/flowmade-one/iris/ui"
+)
+
+// Global auth state to demonstrate route guards
+var isAuthenticated = reactive.NewSignal(false)
+
+func main() {
+	// Define routes with their handlers and guards
+	routes := []navigation.Route{
+		{Path: "/", Handler: homePage},
+		{Path: "/about", Handler: aboutPage},
+		{Path: "/users", Handler: usersPage},
+		{Path: "/users/:id", Handler: userDetailPage, Guards: []navigation.RouteGuard{
+			navigation.NumericIdGuard(),
+		}},
+		{Path: "/admin", Handler: adminPage, Guards: []navigation.RouteGuard{
+			navigation.AuthGuard(func() bool { return isAuthenticated.Get() }),
+		}},
+	}
+
+	// Create router and set up navigation
+	router := navigation.NewRouter(routes)
+	router.SetNotFoundHandler(notFoundPage)
+	navigation.SetGlobalRouter(router)
+
+	// Mount the app with router support
+	ui.NewAppWithRouter(router)
+
+	// Keep the application running
+	select {}
+}
+
+// homePage renders the landing page with navigation links
+func homePage(params map[string]string) ui.View {
+	return pageLayout("Home",
+		ui.VerticalGroup(
+			ui.TextFromString("Welcome to the Iris Multi-Page Demo").
+				Color("#333").
+				Padding("16px"),
+			ui.TextFromString("This example demonstrates client-side routing with:").
+				Color("#666").
+				Padding("8px"),
+			ui.VerticalGroup(
+				ui.TextFromString("- Multiple routes and page navigation").Color("#888"),
+				ui.TextFromString("- Route parameters (see /users/:id)").Color("#888"),
+				ui.TextFromString("- Route guards for protected pages").Color("#888"),
+				ui.TextFromString("- Browser history integration").Color("#888"),
+			).Padding("8px 24px"),
+			ui.TextFromString("Use the navigation bar above to explore.").
+				Color("#666").
+				Padding("16px"),
+		),
+	)
+}
+
+// aboutPage renders information about the demo
+func aboutPage(params map[string]string) ui.View {
+	return pageLayout("About",
+		ui.VerticalGroup(
+			ui.TextFromString("About Iris Navigation").
+				Color("#333").
+				Padding("16px"),
+			ui.TextFromString("The navigation package provides:").
+				Color("#666").
+				Padding("8px"),
+			ui.VerticalGroup(
+				ui.TextFromString("Router - Define routes with path patterns and handlers").Color("#888"),
+				ui.TextFromString("RouteGuard - Protect routes with custom logic").Color("#888"),
+				ui.TextFromString("HistoryManager - Integrate with browser history").Color("#888"),
+				ui.TextFromString("Link - Create navigational elements").Color("#888"),
+				ui.TextFromString("Navigate/Back/Forward - Programmatic navigation").Color("#888"),
+			).Padding("8px 24px"),
+		),
+	)
+}
+
+// usersPage renders a list of users with links to their detail pages
+func usersPage(params map[string]string) ui.View {
+	users := []struct {
+		ID   string
+		Name string
+	}{
+		{"1", "Alice"},
+		{"2", "Bob"},
+		{"3", "Charlie"},
+		{"4", "Diana"},
+	}
+
+	var userLinks []ui.View
+	for _, user := range users {
+		// Capture user in closure
+		u := user
+		userLinks = append(userLinks,
+			navigation.Link(fmt.Sprintf("/users/%s", u.ID),
+				ui.TextFromString(fmt.Sprintf("View %s (ID: %s)", u.Name, u.ID)).
+					Color("#0066cc"),
+			).Padding("8px").Cursor("pointer"),
+		)
+	}
+
+	return pageLayout("Users",
+		ui.VerticalGroup(
+			ui.TextFromString("User Directory").
+				Color("#333").
+				Padding("16px"),
+			ui.TextFromString("Click a user to see their details:").
+				Color("#666").
+				Padding("8px"),
+			ui.VerticalGroup(userLinks...).Padding("8px"),
+		),
+	)
+}
+
+// userDetailPage shows details for a specific user using the :id parameter
+func userDetailPage(params map[string]string) ui.View {
+	userID := params["id"]
+
+	// Simulated user data
+	userData := map[string]struct {
+		Name  string
+		Email string
+		Role  string
+	}{
+		"1": {"Alice", "alice@example.com", "Admin"},
+		"2": {"Bob", "bob@example.com", "User"},
+		"3": {"Charlie", "charlie@example.com", "User"},
+		"4": {"Diana", "diana@example.com", "Moderator"},
+	}
+
+	user, exists := userData[userID]
+	if !exists {
+		return pageLayout("User Not Found",
+			ui.VerticalGroup(
+				ui.TextFromString(fmt.Sprintf("User with ID %s not found", userID)).
+					Color("#ff4444").
+					Padding("16px"),
+				ui.Button(func() {
+					navigation.Navigate("/users")
+				}, ui.TextFromString("Back to Users")).
+					Padding("8px"),
+			),
+		)
+	}
+
+	return pageLayout(fmt.Sprintf("User: %s", user.Name),
+		ui.VerticalGroup(
+			ui.TextFromString(fmt.Sprintf("User Details (ID: %s)", userID)).
+				Color("#333").
+				Padding("16px"),
+			ui.VerticalGroup(
+				ui.TextFromString(fmt.Sprintf("Name: %s", user.Name)).Color("#666"),
+				ui.TextFromString(fmt.Sprintf("Email: %s", user.Email)).Color("#666"),
+				ui.TextFromString(fmt.Sprintf("Role: %s", user.Role)).Color("#666"),
+			).Padding("8px 24px"),
+			ui.HorizontalGroup(
+				ui.Button(func() {
+					navigation.Back()
+				}, ui.TextFromString("Go Back")).Padding("8px"),
+				ui.Button(func() {
+					navigation.Navigate("/users")
+				}, ui.TextFromString("All Users")).Padding("8px"),
+			).Padding("16px"),
+		),
+	)
+}
+
+// adminPage is a protected route that requires authentication
+func adminPage(params map[string]string) ui.View {
+	return pageLayout("Admin",
+		ui.VerticalGroup(
+			ui.TextFromString("Admin Dashboard").
+				Color("#333").
+				Padding("16px"),
+			ui.TextFromString("Welcome to the protected admin area!").
+				Color("#28a745").
+				Padding("8px"),
+			ui.TextFromString("This page is protected by an AuthGuard.").
+				Color("#666").
+				Padding("8px"),
+			ui.Button(func() {
+				isAuthenticated.Set(false)
+				navigation.Navigate("/")
+			}, ui.TextFromString("Logout")).
+				Padding("8px").
+				Background("#dc3545").
+				Foreground("#fff"),
+		),
+	)
+}
+
+// notFoundPage renders when no route matches
+func notFoundPage() ui.View {
+	return pageLayout("404",
+		ui.VerticalGroup(
+			ui.TextFromString("404 - Page Not Found").
+				Color("#ff4444").
+				Padding("16px"),
+			ui.TextFromString("The page you are looking for does not exist.").
+				Color("#666").
+				Padding("8px"),
+			ui.Button(func() {
+				navigation.Navigate("/")
+			}, ui.TextFromString("Go Home")).Padding("8px"),
+		),
+	)
+}
+
+// pageLayout provides consistent page structure with navigation
+func pageLayout(title string, content ui.View) ui.View {
+	return ui.VerticalGroup(
+		navBar(),
+		ui.VerticalGroup(
+			ui.TextFromString(title).
+				Color("#333").
+				Padding("8px").
+				Background("#f0f0f0").
+				Width("100%"),
+			content,
+		).Padding("16px"),
+	).MinHeight("100vh")
+}
+
+// navBar creates the navigation header with links
+func navBar() ui.View {
+	return ui.HorizontalGroup(
+		navigation.Link("/", ui.TextFromString("Home").Color("#fff")),
+		navigation.Link("/about", ui.TextFromString("About").Color("#fff")),
+		navigation.Link("/users", ui.TextFromString("Users").Color("#fff")),
+		authButton(),
+	).Background("#333").Padding("8px 16px").AlignItems("center")
+}
+
+// authButton shows login/admin based on auth state
+func authButton() ui.View {
+	return ui.Button(func() {
+		if isAuthenticated.Get() {
+			navigation.Navigate("/admin")
+		} else {
+			isAuthenticated.Set(true)
+			navigation.Navigate("/admin")
+		}
+	}, ui.TextFromFunction(func() string {
+		if isAuthenticated.Get() {
+			return "Admin"
+		}
+		return "Login"
+	}).Color("#fff")).Background("transparent").Border("1px solid #fff").Padding("4px 12px").Cursor("pointer")
+}